<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body>
<form><p>普通HTML中（HTML4）</p><p><label>UserName:<input name=search id="search" type="text"/></label></p></form>
<script type="text/javascript">
document.getElementById('search').focus()
</script>

<form><p>HTML5中</p><p><label>Search:<input name=search autofocus/></label></p></form>
</body>
</html>
